Molecular Level Understanding of Super-Critical Water Desulfurization

The goal of our work is to develop molecular level understanding of super-critical water desulfurization (SCWDS) process. SCWDS is a very attractive technique for removing sulfur from high sulfur containing feedstocks such as heavy oil and bitumen. However, fundamental understanding of SCWDS of different types of sulfur compounds present in such feedstocks is yet to be developed. In the present work, we have studied the SCWDS performance of several model sulfur compounds constituting of aliphatic sulfides (cyclic, and non-cyclic), aromatic sulfides and thiophenic compounds using a continuous flow well-mixed reactor system. It is found that the extent of desulfurization depends on the molecular structure of the sulfur compounds. Aliphatic and aromatic sulfides undergo significant desulfurization compared to thiophenic sulfur compounds. Further, aliphatic and aromatic sulfides, depending on their molecular structure, exhibit distinct reactivity and mechanism of decomposition under SCW environment. High quality kinetic data was also obtained for the desulfurization of these compounds using continuous flow reactor system. This knowledge will provide sound technological basis for developing commercial SCWDS process.